The main challenge of the architectural design lay in retention of the external appearance of the historic, U-shaped ensemble, composed of Lenbach villa, studio building and gallery wing. The listed garden and historic Lenbach rooms were also to remain untouched.

The original access route through the garden and up a flight of steps leading to the villa no longer met the requirements of a contemporary museum attracting increasing numbers of visitors. A further key requirement was therefore to provide barrier-free access.

A fundamental reorganisation of the rather confusing prevailing spatial structuring – both in terms of interior space and in an urban development context – was also urgently needed.

Photograph: Nigel Young / Foster + Partners

Photograph: Nigel Young / Foster + Partners

Foster removed a two-storey extension dating back to the early 70s and replaced it with a three-storey rectangular structure. The new entrance to Lenbachhaus is located at the interface between the new extension and Lenbach studio, leading visitors into an atrium lobby from where the various parts of the collection can be reached. Another special feature of the atrium is the incorporation of a section of the now exposed and renovated external studio façade: the old sculptural structure is articulated within the new.

View of the atrium with the spiral vortex sculpture "Wirbelwerk" by Olafur Eliasson. Photograph: Nigel Young / Foster + Partners

A guest in the modern era: the exposed section of the historic villa presents itself in the atrium as a "sculptural" object. Photograph: Nigel Young / Foster + Partners

The location of the atrium has shifted the orientation of Lenbachhaus towards a newly created open space with a view of the Propylaea and the Königsplatz. Visitors coming from the museum district, the city centre or the main railway station, are now received with a welcoming gesture. The reorganisation has also resulted in closer proximity of "Kunstbau", a subterranean exhibition hall associated to Lenbachhaus.

The ground floor of the new construction by Foster + Partners is completely transparent and oriented towards the new piazza. A restaurant, accessible from inside and outside the premises, also opens up to this landscaped space. This floor moreover accommodates a large room for lectures or seminars, as well as the museum's very first shop, located in a long and narrow tract at the back of the villa.

Post-1945 art is presented directly above on the first floor, while the impressive "Der Blaue Reiter" (Blue Rider) collection is given an adequate setting in a newly created second floor.

The collection "Der Blaue Reiter" is located on the second floor. Photograph: Nigel Young / Foster + Partners